Method of making counterbalanced crank shafts



Dec. 11, 1923. 1,476,811

L. w. GREVE METHOD OF MAKING COUNTERBALANCED CRANK SHAFTS Filed 0c}. 27 1921 2 Sheets-Sheet 1 Dec. 11, 1923. 1,476,811

L. w. GREVE METHOD OF MAKING COUNTERBALANCED CRANK SHAFTS Filed Oct. 27, 1921 2 Sheets-Sheet 2 Patented Dec. 11, 1923.

)PUNITED, STATE-S LOUIS W. GBEVE, OI CLEVELAND, OHIO, ASSIGNOR'TO THE CHAMPION MACHINE & I

PATENT OFFICE.

FORGING COIPANY, OF CLEVELAND, OHIO, A. CORPORATION OF OHIO.

OI MAKING COUNTERBALANCED CRANK SHAF'IS.

Application filed October 27, 1921. Serial No. 510,988.

To all whom it may concern:

Be it known that I, Louis W. Ganvn, a citizen of the United States residlng at Cleveland in the county of (luyahoga and State of hio, have'invented a certaln new and useful Improvement in Methods of Making Counterbalanced Crank Shafts, of which the following is a full,'clear, and exact description.

This invention relates to a method of making counterbalanced crank shafts which are commonly employed on high speed engines, particularly internal combustlon engines of various kinds of automotive vehitill cles.

It is customa at the present time to counterbalance t e off-center weights of crank shafts by attaching thereto by welding or otherwise, counterweights having arc'or sector shaped outer portions which lie in planes transverse to the axis of the counter shaft diametrically opposite the parts to be counterbalanced. The counterweights are attached to the crank shaft after the latter is forged, for the reason that the shape and location of the counterweights would require forging dies having much deeper depressions than is permissible in forging practice, particularly when forging crank shafts.

As far as I am aware, no method has heretofore been devised whereby counterweighted crank shafts could be forged with the counterweights produced thereon in the forging operation, having in mind the limitations of cost, and the required constructional shape or design of the crank shaft to be produced.

The principal object of the invention is to avoid the necessity of separately applying counterweights to a crank shaft after it has been forged, and to provide a method whereby a crank shaft with integral counterweights shaped and located as required to pro uce the best results,'can be produced with the counterweights formed on the crank shaft in the forging operation.

In accordance with the present invention, the counterweight masses are forged integrally with the crank-shaft but substantially within the confines of the upper and lower surfaces of the crank shaft when forged, and in a subsequent step the countransversel of the crank shaft axis and have the s ape and position required.

In the preferred embodiment of the present invention, the counterweights or counterweight masses are, followm the first forging step wherein the era shaft is forged, *sulnected to an upsetting action by sultable d1es whichcauses the metal of the counterweight to be extended laterally, and p 'to assume the final shape and position of crank shaft by this improved method, and

showing dies which may be utilized to advantage 1n the re-forming and repositioning of the counterweight masses, Fig. l is'a side view of the crank shaft as produced by the forging dies employed in the first ste of the process, wherein the crank shaft wit the mtegral counterweights is forged; Fig. 2 is a v1ew showing in section, dies which mayf be utilized in the next step of the method wherein the counterweight masses are reformed and re-positioned; Fig. 3 is a similar. view of the same with the dies of Fig. 2 closed; Fig. 4 is an end view of the dies showing the crank shaft in section; Figs. 5 and 6 are end views through the crank shaft before and after the counterweight masses have been re-formed and repositioned by the second step of the process; and Fig. 7 1s a side view of the completed crank shaft.

In the drawings I have shown a fourthrow three-bearing crank shaft, but the invention may be utilized equally well with crank shafts having a different number of bearing portions and any desired number of throws or crank pins, the particular crank shaft'herein illustrated, being shown and described for convenience only.

In Fig. 1 I have shown a crank shaft as produced method. crank shaft has in this instance, (but not necessarily as above states-g three bearing portions 10, and four era by the first main step of the T is' pin portions 11. Additionally this crank shaft has four counterweights or counterweight masses 12, opposite the off-center weights to be counterbalanced, and in this instance located opposite the arms or cheeks 13 between each bearing portion and the adjacent crank pin 11, and on opposite sides of the axis of the crank shaft to that on which the associated checks or arms extend. These counterweights produced on the crank shaft in the first forging operation are preferably no thicker in a lateral'direction) than the crank s aft itself. In-

-On the other hand, these counterweights or counterweight masses 12 have lugs or body portions 12 elongated or thickened longitudinally of'the crank shaft, these being connected by relatively thin neck portions 12 to the crank shaft. Preferably the bod portion or boss 12 of each counterweigll t projects chiefl in one direction from its associated nee port-ion and to facilitate the upsetting of these bosses so as to expand the metallaterall I prefer that in a four-throw crank sha t'as herein illustrated, the bosses or body portions of .two of the counterweights project from the neck portions 12 in one direction, or toward one end of the crank shaft, and the other two project in the opposite direction this being done to permit the upsetting of two counterweights at one time, if that procedure should be "desired.

In the next or subsequent ste of the method the bosses or axially thick ody portions of the counterweights are upset, and the metal is caused to flow laterally in suitable dies having formin depressions such as to give the counterweights, or the outer ortions thereof, the desired sector-shape illustrated in Figs. 6 and 7 and designated.

12 with the sector-shaped portions extending'now laterally beyond the confines of the crank shaft, and to lie in planes transverse to the axis of the crank shaft as is desired. This may be done in various ways and b various kinds of upsetting dies. The dies i lustrated in the drawin include gripping members 14 which are dzsigned to envelo and to tightly grip the crank shaft, in this instance for about one-half the length thereof, and the dies include also, movable sections 15, which when actuated under suitable pressure re-forms or re-positions the metal of the. bosses or body portions 12*, as above explained, and causes the metal of the bosses to assume the desired shape and location by causing it to flow and completely fill the forming depressions 14 and 15 in the gripping and movable sections of the dies.

7 With the upsetting dies herein illustrated,

the bosses 12" of the two oounterweights are simultaneously upset as before stated, this being made possible by recessing at the point 15 the two halves of the lower movable die section 15, illustrated in Fig. 2, so as to provide clearance to enable. the inner of the two counterweights to be upset. If the counterweights are upset in pairs, with dies such as shown, or otherwise formed if desired, as soon as one pair of counterwei hts is upset, the crank shaft is reversed in t e dies so that the other pair may be upset.

However, it is to be understood that the unterweights may be u set individually, or one at a time instead 0 in pairs as herean illustrated, and by any suitable form of ice.

It will be understood that this second step of the method, wherein the counterweifghts are upset so as to re-position and recm the metal, is conducted immediately after the for ing of the crank shaft in the first ste of t e method, and while the metal is still lot and capable of being caused to flow in the forming depressions of the dies utilized in the second step of the method, but, of course, the crank shaft may be reheated for this purpose if necessary or desirable.

Thus by this method there is produced a crank shaft wherein the counterweights are formed integral with the body of the crank shaft, and I am enabled to avoid the ex nsive operations of subsequently attac ing the counterweights, and at the same time I produce a crank shaft wherein the oil'- center weights are as perfectly counterbalanced as possible, and wherein there is total absence of liability of the counterweight being; thrown by centrifugal force from the cran shaft. At the same time by this method a crank shaft can be produced at a reasonably low cost.

I aim in my claims to cover all modifications of the method herein disclosed, which do not involve a departure from the spirit and scope of the invention as defined in the appended claims.

Having described my invention, I claim:

1. The method of making counterbalanced crank shafts which'consists in forgmg the shaft with integral counterweights thereon, and subsequently causing the metal to flow laterally so that the counterweights will be extended laterally a greater distance than when forged.

2. The method of making counterbalanced crank shafts which consists in forging the crank shaft with integral counterweights thereon, subsequently decreasing the thickness of the counterwei ht masses axially of the counter shaft, an spreading or extending them laterally of the crank shaft.

Ill

, 3. The method of making counterbalanced crank shafts which comprises forgingthe crank shaft with integral counterweights thereon, and-upsetting the counterweight masses so as to spread them laterally.

e. The method of making counterbalanced crank shafts which consists "in forging the crank shaft with integral counter- Weights thereon, and subsequently changing the shape of the counterweights to cause them to be extended laterally a greater distance than when forged.

In testimony whereof, I hereunto affix my signature.

LOUIS W. GREVE. 

